In purely optical communication networks, in particular with WDM (wavelength division multiplexing) communication networks, data transmission channels having various wavelengths are used to produce data connections. As desired by the network customer, network operators are supposed to provide optical logical connections, for example short-term ones, between arbitrary terminal points within the communication network. Thus, a portion of the optical connections existing in an optical communication network has a static characteristic and another portion has only a brief life span. For the production of short-lived optical connections of this sort, up to now, cross-connectors or through-switching means, operating electronically, have been used, wherein, in particular in the future for the exploitation of the existing network capacities, optical through-switching means, also called add-drop multiplexers, which can be remotely configured automatically, are provided in the respective concentration points of the communication network. However, the use of these remotely configurable optical through-switching means is very cost-intensive and requires a high maintenance expense.
In addition, in the design of the optical forward/return connection in optical communication networks, for reasons of security of the communication network, care is taken that the optical forward/return connection and the corresponding optical xe2x80x9cprotectionxe2x80x9d forward/return connections are set up in different optical fibers that are routed via geographical connection paths that run in spatially separated fashion. In this way, in the case of a break in a fiber, it is ensured that a reliable substitute connection is available for the data transmission.
In particular, individual network customers request that, in communication networks having a double-star topology, optical forward/return connections that are provided only for a short time period, and the additional optical protection forward/return connections, can be set up or, respectively, dismantled automatically and from a control point that is remote from the point of connection.
In known optical communication architectures, for this purpose, through-switching means that can be remotely configured are provided both at the two xe2x80x9cstar-pointxe2x80x9d network nodes and also at additional network nodes of the optical communication network. Thus, the network nodes are connected to concentration points located between the individual geographical connection paths. Due to the large number of these remotely configurable through-switching means provided at the network nodes, there results a high degree of complexity of the optical communication network, which contributes, in particular, to an increased production expense and a lower degree of reliability of the communication network. In addition, given an optically transparent realization of the communication network, an optical power control unit is to be provided in addition to the remotely configurable through-switching means for the matching of the power of the optical signal received in the respective network node. This also leads to an increase in the complexity of the overall system and to a considerable increase in the production expense for the optical remotely configurable communication network.
An underlying object of the present invention is to construct a remotely configurable optical communication network in such a way that remotely configurable through-switching means are to be provided only at the two xe2x80x9cstar pointxe2x80x9d network nodes of the communication network in order to ensure, for all logical connections planned in the network and provided between the individual network nodes, at least two logical connection paths that run in a geographically separated fashion. The object is achieved on the basis of a remotely configurable optical communication network having at least two xe2x80x9cstar pointxe2x80x9d network nodes and having a plurality of network nodes connected respectively to the at least two xe2x80x9cstar pointxe2x80x9d network nodes via logical connections, each logical connection being realized by defined connection paths with each path containing at least one connection path segment, each logical connection having a working connection path routed via a xe2x80x9cstar pointxe2x80x9d network node and a geographically different substitute connection path, routed via the additional xe2x80x9cstar pointxe2x80x9d network node, the xe2x80x9cstar pointxe2x80x9d network nodes being provided with optical through-switching means for switching through the logical connection via the working connection path and the substitute connection path between the respective network nodes.
The essential aspect of the inventive remotely configurable optical communication network is that the remotely configurable optical communication network, which has at least two xe2x80x9cstar pointxe2x80x9d network nodes and a plurality of network nodes connected, respectively, via logical connections to the at least two xe2x80x9cstar pointxe2x80x9d network nodes. The logical connections are realized by defined connection paths that contain at least one connection path segment. In addition, for each logical connection, a working connection path, routed via a xe2x80x9cstar pointxe2x80x9d network node, and a geographically different substitute connection path, which is routed via an additional xe2x80x9cstar pointxe2x80x9d network node, are realized, and the optical through-switching means are provided in each of the xe2x80x9cstar pointxe2x80x9d network nodes for switching through the logical connections, respectively, via the working connection path and the substitute connection path between the respective network nodes. Advantageously, for each existing or planned logical connection between two network nodes, a working connection path that is provided for an active connection fiber and a substitute connection path, that is routed in a different geographical fashion and is provided for a redundant connection fiber, are respectively used for the transmission of the optical signals, whereby the working connection path provided for the active connection fiber is routed via a first xe2x80x9cstar pointxe2x80x9d network node, and the substitute connection path provided for the redundant connection fiber is routed via a second xe2x80x9cstar pointxe2x80x9d network node. An allocation of this sort of the connection paths provided for active and redundant data transmission and the connection of each network node with one of the xe2x80x9cstar pointxe2x80x9d network nodes via logical connections makes it possible, with the aid of optical remotely configurable through-switching means connected in the xe2x80x9cstar pointxe2x80x9d network nodes, to reconfigure the connection paths provided for the forward/return connections in the xe2x80x9cstar pointxe2x80x9d network node or to switch through connection paths or separate them. In this way, no remotely configurable through-switching means are required in the respective network nodes in order to connect the individual network nodes of the optical communication network with another according to their logical connections in such a way that the two connection paths that run spatially separate from one another are respectively provided for the active and for the redundant data transmission. In addition, the cost-intensive preparation of optical power control units in the individual network nodes can be omitted, and there advantageously results a reduction in the complexity of the communication network, due to the more advantageous configuration of the communication network. In addition, connection paths standardly consist of a plurality of connection path segments, often called xe2x80x9cductsxe2x80x9d by those skilled in the art. xe2x80x9cDuctsxe2x80x9d are to be understood as shafts in which optical fibers are routed from an optical add-drop multiplexer to another optical add-drop multiplexer. In the inventive remotely configurable optical communication network, a multiple use of a duct for the working connection path and for the substitute connection path is avoided, and by this means the failure of the logical connection in case of an optical fiber breakage is avoided.
The inventive remotely configurable optical communication network thus presents a communication network that is optimized with respect to the exploitation of the existing or planned connection paths, in which, without the aid of additional remotely configured through-switching means provided in the individual network nodes, an extremely flexible switching through of short-term connections with a 1+1 power protection, becomes possible via two connection paths routed in spatially separate fashion.
According to a further construction of the inventive remotely configurable optical communication network, a computing unit or means is provided for the formation of an item of data traffic relation information, representing the expected data traffic relation between the individual network nodes, and for the calculation of the working connection paths routed via the xe2x80x9cstar pointxe2x80x9d network nodes. In addition, the computing unit or means is provided for the calculation of the geographically various substitute connection paths that are routed via the additional xe2x80x9cstar pointxe2x80x9d network nodes, and for the formation of an item of connection path information. Advantageously the data traffic relation information required for the planning of the inventive remotely configurable optical communication network is formed in the computing unit in the form of a correlation matrix, whereby the elements thereof define unambiguously those network nodes located in the communication network between which a logical connection is planned, and the network nodes among which no logical connection is provided. In addition, the working connection paths and the substitute connection paths provided for the planned logical connections between the network nodes are calculated in the computing unit and an item of the connection path information is formed therefrom. The items of information calculated in the computing unit are used for the optimal configuration of the inventive optical communication network with respect to the optimal exploitation of the existing connection path resources.
Additional advantageous constructions of the invention can be seen from the following description of the preferred embodiments, the drawings and claims.